Other Long-Term Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Other Long-Term Liabilities [Line Items]
Supplemental employees' retirement plan (SERP)	$ 141,546	$ 85,835
Total	45,647	47,038
Other Liabilties [Member]
Other Long-Term Liabilities [Line Items]
Supplemental employees' retirement plan (SERP)	9,818	9,091
Deferred compensation	14,601	13,472
Long-term incentive plan	7,527	7,051
Noncurrent income taxes payable	2,300	3,332
Environmental remediation liability	7,370	8,256
Other	4,031	5,836
Total	$ 45,647	$ 47,038